Heidegger's purpose is to show how and why dying is not just an external contingency, a de facto stroke of bad luck that befalls us at the end of our lives, but a structural dimension of existence, a kind of necessary limit or boundary constitutive of being-in-the-world. For Bernard Williams, as for both common sense and the philosophical tradition, that is, dying is simply the final event marking the termination of a life, the transition from being alive to being dead. Heidegger writes, 'anxiety, as a fundamental disposedness, belongs to the essential constitution of Dasein's being-in-the-world', and 'anxiety always already latently determines being-in-the-world'. Heidegger maintains that Dasein always has an understanding of it and is always in some mood or other. By recognizing the claim about the closing down of possibilities as a generic, the chapter helps to make sense of Heidegger's characterization of authentic resoluteness as a 'readiness for anxiety'.